(Not Applicable)
This invention relates generally to battery charging systems, and more particularly to marine battery charging systems.
Marine craft frequently have more than one engine. Each engine typically has its own alternator and battery to create separate electrical systems, such that the failure of one electrical system will not totally disable the marine craft. These batteries are sometimes referred to as start or crank batteries because they are utilized to crank the respective engine during the engine starting procedure. Another battery, sometimes referred to as the house battery, is provided for powering the various electronic accessories and non-engine equipment of the vessel. These accessories can include electronic equipment such as radar, LORAN, and radios, as well as pumps, cooling devices such as refrigerators, air conditioners and fans, electric motors, and bait well aerators. The alternators associated with each engine typically are sufficient to maintain a proper voltage in each of the associated start batteries, provided that the engines are operating at sufficient RPMs to drive the alternators. The house battery is typically connected in parallel with one of the start batteries, such that the house battery will be charged by the respective engine alternator.
Under certain conditions, where there is low alternator output such as when trolling at low speeds, the associated start battery and house battery can become drained. The situation can become particularly acute if there is high demand on the house battery through the operation of electronic devices that are connected to the house battery. In such instances, the charge on the associated start battery may fall below levels which are necessary to start the engine. Battery voltage monitors and battery switching systems have been provided for monitoring the voltage in batteries and switching among batteries if the voltage level in a battery falls below a threshold value. Such systems, however, sometimes result in both start batteries becoming drained to near the threshold level, and the system repeatedly switches between the near-threshold voltage batteries such that no battery becomes fully recharged.
This reduction in start battery charge presents additional problems in new marine engines that utilize electronic engine control. The electronic engine control systems require a reliable battery source to power the control electronics. Thus, when the crank battery falls below a certain threshold, not only is there insufficient power to start the engines, but the electronic controls will shut down the engine when the power level is too low for the electronic controls themselves. As a result, major marine engine manufacturers specify that external charging systems connected to multiple engines should not be arranged to draw charge power from the alternators or other charging sources of more than one engine at a time. Accordingly, there is a need for an external charging system that utilizes the charging capabilities of more than one engine while observing this manufacturer specification.
A system for charging batteries includes a first charge source for connection to a first engine; at least a second charge source for connection to at least a second engine; a first start battery connected to said first charge source; at least a second battery connected to said second charge source; at least a third battery; and at least one switch adapted in a first mode of operation to connect said third battery to said first charge source, and in a second mode of operation to connect said third battery to said second charge source.
A voltage monitor is preferably provided to monitor the voltage in at least the first battery and the second battery. The switch is responsive to the voltage to switch the third battery between a connection to the first charge source and a connection to the second charge source. The switch can switch the third battery from the first charge source if the voltage in the first battery falls below a threshold voltage, and can switch the third battery from the second charge source if the voltage in the second battery falls below a threshold voltage. A timer can be provided for maintaining the connection between the third battery and the first charge source or the second charge source for a given period of time prior to switching to another charge source.
The invention is particularly adaptable to marine engine systems. The first and second charge sources can be alternators powered by the engines. The first battery and second battery can be start batteries, and the third battery can be a house battery. The house battery is connected to marine electronics such as radar, LORAN, radios, pumps, cooling devices, electric motors and bait well aerators.
A switch assembly according to the invention includes structure for connection to a first charge source; structure for connection to a second charge source; structure for connection to a first battery, and for connecting the first charge source to the first battery; structure for connection to a second battery, and for connecting the second charge source to the second battery; structure for connecting to a third battery; and at least one switch for switching between a first mode of operation in which the third battery is connected to the first charge source, and a second mode of operation in which the third battery is connected to the second charge source.
The switch can also include control logic for switching the third battery between the first charge source and the second charge source responsive to the voltage in the respective first battery and second battery. The switch assembly will switch the third battery from the first charge source if the voltage in the first battery falls below a threshold level. The switch assembly will switch the third battery from the second charge source if the voltage in the second battery falls below a threshold voltage. A timer can be provided to maintain the switch in a position for a given length of time to prevent repeated switching between charge sources. The switch assembly is particularly useful in the marine environment. The first and second batteries can be start batteries. The third battery can be a house battery. The first and second charge sources can be alternators, powered by marine engines.
According to another optional aspect of the invention, the charging system can be arranged so that if the voltage levels of both engines are below the threshold level when checked by the monitoring system, the charging system can switch to a third configuration. In the third configuration, the third battery can be isolated from both charge sources. While any further charging of the third battery is terminated during this third configuration, both charge sources can then attempt to recharge to the first and second engine batteries, without further loading from the third battery. Optionally, switching to this third configuration can be accompanied by an alarm, either visual, audible or both, to alert the user that the third battery is no longer being charged, presenting the risk of failure of accessories powered by the third battery. More importantly, the alarm can alert the user that the crank batteries have both fallen below the threshold voltage and risk shutting down the engines, in case of electronic controlled engines, and may not have sufficient power to crank the engines after shut-down. The user can address the low voltage situation, for example, by running the engines at higher RPM""s to recharge the two crank batteries.
If through user intervention or through relief from charging the third battery, one of the crank batteries returns to a voltage level above the threshold voltage, the charging system can detect this increased voltage through the monitoring system and resume the charging connection to the third battery. The criterion for re-establishing the charge to the third battery can be set to occur when either one of the crank batteries returns to a voltage level above the threshold level or only when both crank batteries return to the proper voltage level.
A method for charging batteries includes the steps of:
connecting at least a first battery to at least a first charge source;
connecting at least a second battery to at least a second charge source;
connecting at least a third battery to a switch assembly;
monitoring the voltage in at least the first battery and the second battery; and,
switching the third battery from the first charge source to the second charge source if the first battery has a voltage below a threshold voltage, and
switching the third battery from the second charge source to the first charge source if the second battery has a voltage below a threshold voltage.